TxManager is AutoCloseable and releases what it was built on: JdbcTxManager its data source when closeable, HibernateTxManager its session factory and then the data source Hibernate was handed, which Hibernate itself never closes. DataExtension registers the close as an onClose callback, so a stopped app no longer leaves its pool connected. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>